A pressure cooker cooks food faster because increasing the pressure inside
Correct answer: D. raises the boiling point of water above 100 degrees Celsius
- A. lowers the boiling point of water
- B. removes all the air from the vessel
- C. increases the amount of steam produced
- D. raises the boiling point of water above 100 degrees Celsius
Explanation
A liquid boils when its vapour pressure equals the external pressure, so raising that external pressure means a higher temperature is needed, and water inside a pressure cooker can reach about 120 degrees Celsius. The food cooks faster because the reaction rate rises with temperature, not because there is more steam. At high altitude the reverse problem arises and cooking takes longer.
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About Evaporation, Boiling Point and Vapour Pressure
Evaporation is the escape of higher-energy molecules from a liquid surface, while vapour pressure is the pressure exerted by vapour in equilibrium with that liquid. The topic distinguishes evaporation from boiling and relates both to temperature, intermolecular forces, surface area, atmospheric pressure and the boiling point.
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